1. Field of the Invention
This invention relates to the field of olefin polymerization catalysts, and more particularly, to supported catalysts impregnated with chromium (III) compounds.
2. Description of the Prior Art
Numerous olefin polymerization catalysts are known which utilize a chromium (III) compound in their preparation. The low pressure, high molecular weight olefin polymerization process of U.S. Pat. No. 3,008,943 employs the reaction product of an alcoholate, benzoate or acetylacetonate of chromium with titanium tetrachloride. The unsupported olefin polymerization catalyst of U.S. Pat. No. 3,152,105 is thought to be the reaction product of water, a chromous or chromic carboxylic acid salt and either a trialkylaluminum or a dialkylaluminum hydride. It is believed that the water preferentially reacts with the alkylaluminum compound and the product resulting from this reaction then reacts with the chromous or chromic carboxylic acid salt. U.S. Pat. No. 3,311,596 describes the polymerization of olefins using as catalyst, chromium (III) acetylacetonate. The olefin polymerization catalyst of U.S. Pat. No. 3,349,067 is prepared by oxidizing a chromium (III) acetylacetonate which has been deposited on a carrier to at least partly decompose the compound to chromium oxide wherein at least part of the chromium is in the hexavalent state. According to U.S. Pat. No. 3,392,162, an olefin polymerization catalyst is prepared by milling an organo-alkali metal compound such as butyllithium or sodium aluminum dodecyl in a suitable medium, e.g., diesel oil, with a chromium (III) compound such as chromium (III) acetylacetonate or chromium (III) bromide. U.S. Pat. No. 3,622,522 describes an olefin polymerization catalyst prepared from an organo-gallium and/or organo-tin compound, a chromium (III) compound such as chromium (III) dodecoxide or chromyl (III) methylcyclopentoxide, and a titanium-containing compound. U.S. Pat. No. 3,950,303 describes the preparation of filled polyolefins by reacting an olefin in the presence of a filler upon which there is deposited a chromium (III) compound such as: a C.sub.1 to C.sub.12 ester of chromium, e.g., chromium acetate, chromium oxalate, chromium octoate and chromium sulfate; [Cr(NH.sub.3).sub.5 Cl]Cl.sub.2 ; [Cr(NH.sub.3).sub.6 ]Cl.sub.3 ; hexaurea chromium (III) fluorosilicates [Cr(CON.sub.2 H.sub.4).sub.6 ].sub.2 . (SiF.sub.6).sub.3 3H.sub.2 O; fumarato-chromium (III) nitrates; methacrylato-chromium hydroxide; and methacrylatochromium chloride. The supported chromium (III) compound olefin polymerization catalyst of U.S. Pat. No. 3,953,413, e.g., chromium (III) acetylacetonate on silica, is activated by heating at about 850.degree.-2000.degree. F. in a nonoxidizing atmosphere. U.S. Pat. No. 3,959,178 describes a mixed olefin polymerization catalyst in which two portions of a support impregnated with a chromium (III) compound, for example, chromium (III) acetylacetonate, are each activated at temperatures which are at least 200.degree. F. apart, with the combined activated portions thereafter being treated with a hydrocarbyl aluminum hydrocarbyloxide. The mixed olefin polymerization catalyst of U.S. Pat. No. 3,998,996 is prepared by reacting a chromium (III) compound containing water of crystallization such as a hydrated chromium (III) halide, sulfate or carboxylate, with a metal alcoholate and mixing the resulting complex with an activator.
None of the aforementioned patents disclose or suggest an olefin polymerization catalyst prepared with the reaction product of a chromium (III) carboxylate and an aluminum alkoxide as hereinafter more fully described.